linux-kernel - Re: [patch 071/149] ARM: 6166/1: Proper prefetch abort handling on pre-ARMv6

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Date:	Wed, 7 Jul 2010 23:34:18 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	"Kirill A. Shutemov" <kirill@...temov.name>
Cc:	linux-kernel@...r.kernel.org, alan@...rguk.ukuu.org.uk,
	Anfei Zhou <anfei.zhou@...il.com>,
	Alexander Shishkin <virtuoso@...nd.org>,
	Siarhei Siamashka <siarhei.siamashka@...ia.com>,
	linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org
Subject: Re: [patch 071/149] ARM: 6166/1: Proper prefetch abort handling on
	pre-ARMv6

On Wed, Jul 07, 2010 at 11:56:01AM +0300, Kirill A. Shutemov wrote:
> But it seems that the problem is more global. Potentially, any of
> pmd_none() check may produce false results. I don't see an easy way to fix
> it.

It isn't.  We normally guarantee that we always fill on both L1 entries.
The only exception is for the mappings specified via create_mapping()
which is used for the static platform mappings.

> Does Linux VM still expect one PTE table per page?

Yes, and as far as I can see probably always will.  Hence why we need
to put two L1 entries in one page and lie to the kernel about the sizes
of the hardware entries.
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